For the purpose of preventing the overheating of semiconductor elements such as a power transistor, heat-dissipating greases or sheets having excellent thermal conductivity have conventionally been used between heat-dissipating fins and semiconductor elements.
The heat-dissipating greases are used in large amounts even today, because they can be easily applied on semiconductor elements without being affected by the shapes of the semiconductor elements. However, the heat-dissipating greases have problems that other parts are soiled with the greases and that when electrical or electronic products using such greases are used for a long period of time, the greases exude an oil.
The heat-dissipating sheets, on the other hand, are free from the above problems, i.e., the soiling of other parts and the exuding of an oil. However, the heat-dissipating sheets should be formed so as to fit to semiconductor elements, and they have a problem that they bend when fixed with screws or the like, resulting in poor heat-dissipating properties.
In order to overcome these problems, a method in which a liquid silicone rubber composition is used as a potting compound or an adhesive has been proposed as disclosed in, for example, JP-A-61-157569 (the term "JP-A" as used herein refers to a "published unexamined Japanese patent application"). This composition, however, is disadvantageous in that when the filler content is increased for the purpose of improving its heat-dissipating effect, the resulting composition has too high a viscosity, whereby not only can such a composition not be applied on semiconductors or heat-dissipating fins uniformly, but also air is introduced to impair the heat-dissipating properties.